1. Field of the Invention
The present invention is directed to a splicing connection assembly for retaining separable component parts of a missile, spacecraft or the like, and more particularly, to a threadless connecting arrangement for separable tubular structures of a wide variety of types and kinds, being usable for both military and civilian purposes.
2. Description of the Prior Art
The methods of joining separable tubular members are as diverse as the applications of this type of structure. Small diameter missile sections which are subjected to extreme dynamic and atmospheric environments rely on joining systems which provide both adequate mechanical support and environmental integrity.
A typical joining system for this type of usage employs a number of radially located threaded fasteners to transmit shear forces from one missile section to the next and also to compress an elastomeric environmental seal. Each of such threaded fasteners will typically require one screw, one captive nut and two rivets to retain the captive nut, for a total of four items. If, for example, the missile needs twelve of such fasteners in order to satisfy its environmental requirements, which is not an unreasonable number, the total part count for this joining system rises to forty-eight. It is important to recognize the fact that increased complexity means decreased reliability.
In the commercial area, point-of-sale cost and product liability considerations drive designers and manufacturers to slip fits, clevis pins and through-bolts for the joining of tubular structural members. Slip-fit systems provide a protrusion-free exterior but do not prevent accidental separation of the components. Clevis pins and through-bolts afford positive mechanical retention but their protruding features are often the source of user injury.
By way of additional review it should be mentioned that in the 1960s, a connection assembly design referred to as the Marman Band was proposed, which included a plurality of V-retainers or wedged shaped shoe members that provided a V-clamping to flanges positioned on the exterior surfaces of separable component parts of a spacecraft, for example. A pair of separable tension bands were joined together by a pair of spaced pyrotechnic tension bolts that could adjustably vary the tension in the straps that held the V-band coupling members. The tension straps were utilized to create inwardly radial forces on the V-shaped retainers which would in turn, wedge the flanges of cylindrical housing structures of separable component parts of the spacecraft in an axial direction. This V-band coupling was basically configured to transfer axial loads and bending moments across the resulting structural joint of the connection assembly. Small shear torque loads were transferred across the joint by relying on friction that would exist between the flange surfaces and the retainer wedges.
If the missile or spacecraft was to be subject to considerable forces that would produce large shear torque loads, either keys were inserted between the flanges or the friction load that was applied during the loading of the tension straps, had to be carefully controlled to take into consideration the magnitude of the shear torque forces that were to be expected.
Thus, often the primary connection assembly relied upon for separable spacecraft component parts were V-band couplings that were encircled with tension straps to maintain an axial loading between the spaceship component parts. Usually the friction of the band and the axial loading friction on the flanges or cylindrical structures of the spacecraft component parts were relied upon to handle any shear and torque forces.
I am aware of German Patent No. 966,298 to Raacke entitled "Threadless Connection," which teaches the joinder of two interfitted tubular members by the use of a pair of curved locking rings inserted into an encircling slot created at the juncture of the two members. However, the Raacke patent suffers from the distinct disadvantage of requiring an unnecessarily large joint, in that one embodiment involves an undesirable enlargement of the outer diameter of the device, whereas the other embodiment of the Raacke device involves an enlargement of the interior of the device, at the location of the joint. This internal enlargement necessarily results in a restriction of the lumen or effective passageway through Raacke's tubular members, and therefore a distinct diminishment of the maximum flow that can take place through the tubular members of the Raacke device.
Quite importantly, Raacke utilizes ordinary flat washers at the locations where the flat surfaces of the tubular members meet, thus requiring great precision in the machining of the components that go to make up the circular slot defined at the juncture of the two members. This is because unlike O-rings, the flat washers obviously cannot be compressed to any consequential extent, thus requiring Raacke to insert the pair of curved locking rings into the circular slot at the precise time when the flat washers have been compressed to the greatest extent possible, or otherwise leakage will result.
I am also aware of the Bennett et al U.S. Pat. No. 4,838,491 entitled "Coupling," but unlike Raacke, the Bennett et al device involves the joinder of two threaded members, meaning that relative twisting motion must take place between the two members if leakage at the joint is to be prevented. Bennett et al show the use of a pair of compressible O-rings used to prevent leakage, but both O-rings are necessarily subjected to a very large twisting force at the time the two threaded members are being tightly threaded together. This relative motion of the two threaded members frequently brings about a highly undesirable, twisting type distortion of the O-rings, with consequent leakage.
Both of these teachings fall far short of a threadless connection arrangement for a pair of tubular members, in which a highly desirable amount of compression of one or a pair of O-rings takes place at the time of joinder of the tubular members, thus to bring about a leak-free joint of constant diameter.